The present invention relates to an optical recording medium including a substrate and a signal recording layer provided on the substrate and in which an information signal recorded on the signal recording layer is reproduced optically or by detecting a change of the reflected light focused onto the signal recording layer, and to a disc cartridge encasing the optical recording medium.
As one of the conventional recording media for audio and video information, optical discs, from which recorded information is read using a light beam or to which information is written using a light beam, are widely used. Since such an optical disc is formed from a single plate-like substrate, it can easily be handled and has a larger storage capacity than other recording media such as magnetic tapes, etc. Therefore, the optical discs are widely used as media for recording audio and video information, computer-processed data, etc.
Information processing units, such as computers, have been designed more and more compact with an increasingly smaller internal space of installation for a recording and/or reproducing apparatus using an optical recording medium such as an optical disc or the like. That is, there is a demand for a smaller design of such a recording and/reproducing apparatus.
There are various types of portable or carry-on recording and/or reproducing apparatuses for recording and/or reproduction of audio and video information. For a higher portability, it is also demanded that the apparatuses be of a more compact design.
For such a smaller recording and/or reproducing apparatus, a recording medium used in the apparatus should be correspondingly smaller while having a larger storage capacity.
It is therefore an object of the present invention to provide a novel optical recording medium designed smaller while having a larger storage capacity, and a disc cartridge in which the optical recording medium is encased.
It is another object of the present invention to provide an optical recording medium having a larger storage capacity while contributing to a more compact design of a recording and/or reproducing apparatus in which the optical recording medium is used, and a disc cartridge encasing the optical recording medium.
It is a further object of the present invention to provide an optical recording medium designed smaller and positively mountable on a rotation driving mechanism to be rotatable along with the rotation driving mechanism, and a disc cartridge encasing the optical recording medium.
In an embodiment, an optical recording medium according to the present invention includes a substrate and a signal recording layer provided on the substrate, an information signal being recorded on the signal recording layer. The optical recording medium has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A ratio between the information signal recording area and a non-recording area is 3.4 or more. A storage capacity is at least 2 GB (gigabytes) or more.
The above optical recording medium has formed at the center thereof a center hole around which there is formed an annular table-abutment being convex to one side of the medium and in which a hub or clamping plate is fixed.
In an embodiment, an optical recording medium according to the present invention includes a substrate and a signal recording layer provided on the substrate, wherein an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer. The optical recording medium has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A storage capacity is at least 1 GB or more.
The above optical recording medium has formed at the center thereof a center hole around which there is formed an annular table-abutment being convex to one side of the medium and in which a hub or clamping plate is fixed.
In an embodiment, an optical recording medium according to the present invention has an annular table-abutment for placement on a disc table of a rotation driving mechanism, and a hub which is to be attracted by a magnet disposed on the disc table, whereby the medium can be rotated along with the disc table.
In an embodiment, an optical recording medium according to the present invention is a read-only optical recording medium. It includes a substrate, formed to a thickness of 0.4 to 0.6 mm by injecting resin within a mold prepared by stamping a stamper having formed thereon a pit pattern in which the recording track pitch and smallest-pit length are about 1.4 times larger than those in a first optical recording medium with a storage capacity of at least 2 GB including a substrate, and a signal recording layer provided on the substrate, and in which information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer; and a light-transparent sheet which is 0.05 to 0.1 mm in thickness and having on one side thereof a pit pattern, formed by thermally stamping a pit-pattern stamper, where a signal recording layer is formed. In the optical recording medium, the substrate and sheet are joined to each other with their respective pit-pattern sides placed in a face-to-face relation through a light-transparent layer of 20 to 35 xcexcm. The first optical recording medium having a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm, an information signal recording area defined thereon extending outwardly from a radial position of 12.5 mm or less from the center of the medium, a ratio in diametrical length of 3.4 or more between the information signal recording area and a non-recording area, and a storage capacity of at least 2 GB. It has a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm. An information signal-recorded area defined thereon extends outwardly from a radial position of 12.5 mm or less from the center of the medium. A storage capacity is a half or less of that of the first optical disc recording medium.
In an embodiment, the optical recording medium is a read-only type. It has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium.
In an embodiment, a disc cartridge according to the present invention comprise an optical disc including a substrate; a signal recording layer provided on the substrate and in which an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer, the optical disc having a diameter of 65 mm or less and a thickness of 0.4 to 0.7 mm, an information signal recording area defined thereon extending outwardly from a radial position of 12.5 mm or less from the center of the optical disc, a ratio of 3.4 or more between the information signal recording area and a non-signal recording area, and a storage capacity of at least 2 GB or more; and a rectangular cartridge in which the optical disc is encased. In the disc cartridge, a writing and/or reading access opening is formed in a side thereof to which an optical pickup to focus a light beam on at least the optical disc is opposite through which a radially extending portion of the optical disc is exposed, and a central opening is also formed through which a center hole formed at the center of the optical disc is exposed. The writing and/or reading access opening is formed deviated to one lateral side from the middle point of the front side of the cartridge.
In an embodiment, a disc cartridge according to the present invention encases an optical disc including a substrate and a signal recording layer provided on the substrate, and in which an information signal recorded on the signal recording layer is reproduced by detecting a change of the reflected light focused onto the signal recording layer. In an embodiment, a disc cartridge has a diameter of over 38 mm and under 52 mm and a thickness of 0.4 to 0.7 mm. An information signal recording area extends outwardly from a radial position of 12.5 mm or less from the center of the medium. Its storage capacity is at least 1 GB.
A disc cartridge according to the present invention encasing the above-mentioned read-only optical disc has a reading access opening formed only in a lower half.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.